Just happened. Not progressive. 1. 25% increase in fuel consumption.2. Decreased engine response but runs smooth and quiet. 3. When driving the ECO light goes out at the slightest touch on the accelerator.

All levels checked, Air filter clean. Fully serviced motor that ran perfect up to this point.Any ideas?.

After a decent run feel the wheel centres (be careful - one could be rather hot). If a brake caliper is partially seized, and not releasing fully, this could cause your issues. I would also check the tyre pressures.

After a decent run feel the wheel centres (be careful - one could be rather hot). If a brake caliper is partially seized, and not releasing fully, this could cause your issues. I would also check the tyre pressures.

Thanks. All checked. All fine. I am sure it is an engine, fuel/air or exhaust gas problem.

I would have thought that something along those lines would have shown up as a indication on the dashboard. The warning light is normally triggered if the ECU sees anything untoward. Get your local garage to stick an OBD2 code reader on the system. See if anything is recorded.

I read this thread with interest as our jazz si appears to be the same

Itís not bothered me to the point of asking, but as itís been asked I am interested

The garage that serviced/mot our jazz did say the rear breaks were at 60% used where the front breaks had more on them

I have noticed that the green eco light does have a tendency to go out when driving manually but put cruise control on, and it seems to keep on much longer, with only going out if say the road has a slight incline etc

My mpg shows at the moment as 41mpg but on a run at 80mph it shows approx 46/48 mpg

Our headunit is connected to odbc2, and this shows no issues whatsoever

I do think that on the car pc display for mpg, A tends to show better mpg then B does.

Thanks for your help. Nothing showing on dash. I will have it diagnosed first but I am suspecting EGR problem. Will report back if anything found.

EGR problem traditionally shows up as jerky / uneven running at lower revs, the EGR is closed at low revs and only opens up at higher revs to allow exhaust gasses into the system to 'cool the combustion and reduce Nox emissions - EGR problem normally causes stalling and low power when pulling away, an EGR that is stuck open is like having an air leak in the induction manifold, an EGR stuck closed you would never really notice anything. Many people blank off EGR with a metal plate (available on e-bay).

Low annual mileage / short journeys are normally implicated in EGR problems ( like diesel DPF that block up and fail on low mileage vehicles) where they never get open very often to allow crud to be burnt out of them.

Has this happened straight after a service ? disconnecting battery can reset ECU parameters to basic settings and it can take a few miles to re-train the ECU to optimum. Have you recently filled up from a different service station than normal ? I would try either some 97RON 'cleaning fuel' or a good (over)dose of Redex to clean out system and injectors.

Many thanks Culzeen. I think I will run the tank down a bit and then try the trusted redex. I also suspect that it is running a little hotter than usual as I have noticed the cooling fan seems to be coming on more than it used to.

Running hotter could be due to weak mixture, one annoying thing about Jazz is lack of temperature gauge, although Jocko has a scan gauge plugged into his OBD to display amongst other things engine temperature. Mixture is controlled by oxygen sensors, should be easy for dealer to check. If EGR was stuck it should cool combustion as recirculation exhaust gas reduces oxygen in the cylinder. Have you checked level of coolant in radiator and expansion tank ? I find it easier to check expansion tank level by waiting for dark and shining a torch inside neck of bottle to show coolant more clearly when looking at bottle from outside.

Unless aircon turned on (which makes both the engine and aircon radiator fans operate) I would not expect cooling fans to operate at this time of year.

I'll say again, engine management problems normally manifest themselves with a indication on the Malfunction Indicator Lamp. That's its purpose. Think you need a garage, or dealer, to run a diagnostics check.